[libdvdnav-devel] [Git][videolan/libdvdnav][master] Fix null pointer dereference of cell_playback in play_Cell and play_Cell_post

[Jean-Baptiste Kempf (@jbk)]

Jean-Baptiste Kempf pushed to branch master at VideoLAN / libdvdnav


Commits:
2ffc50b5 by Aaron Wood at 2026-08-07T18:59:38+02:00
Fix null pointer dereference of cell_playback in play_Cell and play_Cell_post

When parsing malformed or obfuscated DVDs where a PGC reports nr_of_cells > 0
but has a NULL cell_playback table, accessing cell_playback triggers a segfault.

This adds a NULL check before dereferencing cell_playback in both play_Cell
and play_Cell_post. If the table is missing, it gracefully bails out via
play_PGC_post(vm), avoiding a crash.

- - - - -


1 changed file:

- src/vm/play.c


Changes:

=====================================
src/vm/play.c
=====================================
@@ -211,6 +211,11 @@ link_t play_Cell(vm_t *vm) {
     return play_PGC_post(vm);
   }
 
+  if ((vm->state).pgc->cell_playback == NULL) {
+    /* Invalid PGC: cell_playback is missing */
+    return play_PGC_post(vm);
+  }
+
   /* Multi angle/Interleaved */
   switch((vm->state).pgc->cell_playback[(vm->state).cellN - 1].block_mode) {
   case 0: /*  Normal */
@@ -274,6 +279,11 @@ link_t play_Cell_post(vm_t *vm) {
   Log3(vm, "play_Cell_post: (vm->state).cellN (%i)", (vm->state).cellN);
 #endif
 
+  if ((vm->state).pgc->cell_playback == NULL) {
+    /* Invalid PGC: cell_playback is missing */
+    return play_PGC_post(vm);
+  }
+
   cell = &(vm->state).pgc->cell_playback[(vm->state).cellN - 1];
 
   /* Still time is already taken care of before we get called. */



View it on GitLab: https://code.videolan.org/videolan/libdvdnav/-/commit/2ffc50b5c37a6ddc086829203fc44e95588198dd

-- 
View it on GitLab: https://code.videolan.org/videolan/libdvdnav/-/commit/2ffc50b5c37a6ddc086829203fc44e95588198dd
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